The present invention relates to an X-ray examination apparatus of the type in which an image of an object is formed through scanning the object by a fan-shaped flat X-ray beam.
One particular advantage in the use of a fan-shaped beam, collimated with respect to the receiver, lies in a considerable decrease of the X-ray diffused by the object itself and thus in an improvement of the quality of the image, only a relatively thin segment or slice of the object to be examined being crossed through by the X-ray beam at each instant.
Images in traditional radiology practices, in certain cases, present difficulty in reading; they do not contain sufficiently accurate informations to perform a reliable diagnosis, especially when the examination concerns body tissues presenting only slight differences of absorption to the X-ray, such as aqueous tissues and adipous tissues, or concern search of bodies in low concentration condition.
U.S. Pat. No. 3,515,874 describes a radiography apparatus producing a substantially monochromatic X-ray beam in order to increase on a negative the contrast presented between certain elements having only slight differences of absorption. This apparatus comprises more particularly a physical filter the nature of which allows, in relation to the energy of the incident electron beam, to obtain an X-ray beam having a spectrum that is reduced in energy or wavelengths, containing the wavelength at which is located an absorption discontinuity characteristic of the physical filter.
This constitutes a considerable improvement, but which in many cases is still insufficient, for example, when it is desired to study, in vascular, very fine vessels concealed in a highly diffusing medium.
The idea upon which the applicant has based the present invention, was that in such cases, several perfectly superimposable images of the same area and comprising different informations would allow to display the presence of these vessels.